<?
	//error_reporting(E_ALL);
	$callback = $_POST["Callback"];
	$folder_name = $_POST["FolderPath"]."/".$_POST["FolderName"];
	
	if(file_exists($folder_name)) {
		echo "
			<script>
				alert('User exist');
			</script>
		";
		exit("");
	}
	
	mkdir($folder_name);
	
	if("$callback"!=""){
		echo "
			<script>
				$callback;		
			</script>
		";	
	}
	
?>

Added